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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1defbab39354ca6a7b2c5f3d05c6816297c301c0e5783dfa20cedbff97c9adf1' 
  AND token = '4j+cDIcdjuvRV6zFyxma9oHsqVjuzdiN5ZHPpRgt5Pg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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