SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc9fdf0159e4ff06dc939b145b1dcd9e973d2c5835b809b4e0a23ca55983cfcb' 
  AND token = 'VtBsxew6YV2mD/8PL2LDVMvYaFeqS82xCTEKQ0qGyEs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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