SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de1c7db26f7c522d8efb29851df7db25ecb839a39e04cf2f77b22204f66b54a7' 
  AND token = 'grTjl619MiFLSMht/Lo7EMNYwJIH/DvuTPK5vrXVZ/A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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