SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7a544817d9bc77dda739893ce9d4021b621f9d5c0223e87b1086dab8a54ebcd0' 
  AND token = '5jLRYtz1FKDlaR9xQiXXjqQvoy/YbPEBthG87UwFQyc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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