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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cf7ac1966de7eac1388912d29596b27e5079f58c3a72a1cc9b7bc7f1b7cd6d78' 
  AND token = 'H6bkr5BYzn89olvrYzfSPkgZ5I1hbSHz4ZdqC1XkiNs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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