SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5688c6ffee6f9d14b14c693b1e1b2f49fac8b3d9758945cab1df355ea95ce1c' 
  AND token = 'GlVi/nFxVgZjdrm91KjmNcZyEG+i2c/vGXspAugKfIo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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