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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'abd0b3d2661bc550b50c89ceb88153f582a3836d4fa0804d59a255a4d36f7cee' 
  AND token = 'Sn1owzUJ2rJ2ObzAwaGNOFG3Lsq+klsWPEpEXW8yfDQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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