SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a762d2f8552a938d2486086b845018fb885bed7b1a1c07f3b4946adec542f04b' 
  AND token = 'e+hkGGCKkOqFvmqaGorg5D+9vlnszu0u9hNwa+OBrQs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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