SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '58ce7b1a9332af71e31817e3c71695293794d9b7a0ebc5be63d0a6706077f09f' 
  AND token = 'Sj91so6v3Ckw3y7AU5Id+iefx8W6dmaB+CCosYCbGSY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}