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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '339ce856662de0d5916d003eb98adf6d80eea72f083b6b5639ab1bd43a5a4a49' 
  AND token = 'f97kc99z9JM30Lkd6UyFvwU/k5AoPYZdWoLdNo2xPto=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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