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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52c754a304417ef23c422c765c749b172832721483ba409a834abf3c52739896' 
  AND token = 'VDPvhv7v4p98covsZQ+s12ZpM7NmiHWYvGmoW84OZdk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}