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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'afb8b4b14205ceacd9cc1bd15c4eb56e2baa827a1b8d68d1b0417c63ad5e7f84' 
  AND token = 'sXwIbTlvQxSuvtOPrRnSf7qfdsS++JA2AFYHtohPw70=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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