SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a46282320d6c895cc3163b10c11fa680796275fe57c76af02e0da8af36b95af' 
  AND token = 'zhB0glVN/LrQAdHTI4/xZqDgSgAMFdximlYGi0RG7mE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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