SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dd76c7082ff765bcb59238a2e9e7ddc962a472693608b5ab929f9089c4d86379' 
  AND token = 'CHEH9Xk/oesAwS7kCq/s8y2IXfR+29QqbdxcyAiLXVo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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