SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f68858ba553fbac0827488fbd50fbeff712e85aabcf0e35c4f710f8f0f61ed6a' 
  AND token = 'IueYPK7moyXyUdUbg0qaDLZlmeRyu6ziOJ4/0mFe/+A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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