SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6046f4945233e223875837ad27110550213c2ab809f0bebca29215fbab5a2b99' 
  AND token = 'uvoQeRBDgR38yAcSFNvOPFfQqcgOFPRDIZyUCpFEraY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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