SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '510997e2551916bf10baab399f3adf016d80d887e22685f22aebf10dfb927278' 
  AND token = 'GRnmgHL2zZycFI+9BeUk7q14dlhNlqmzULLI1sE5zvU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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