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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c9529b601b0c3121d1aeb92f3c99aac5b8b3470d2ad76b81ce478b4da315a49' 
  AND token = 'Ek3kLeHay2PYW8b+PmN5IFH1BWe2r7hqPGJ/7fhhEdI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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