SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ce83aec8ad994f094a4ebcbd6e8ebf38fc3978cb4d9e44d7e50b1c6489ba6f5' 
  AND token = '5VZpxHqfAAFNH/8oTCEmzptZV6xSLsrPYR8vLGQPdKE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}