SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fbb393f4c8f8b7e366a87f7a1c946e1cac3051997c119b0a089f583704251d60' 
  AND token = 'GoN5JNw+qkVS0WwwiG6jl1BfoRygDHujFDhDW7MAZ7g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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