SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '497d7f4d0f5eadb53a226583a0650cdb50c2257b5e77addc723533a491260836' 
  AND token = 'ugtiJLDVZWVB9P+aBvqvo+dz4VgrI8+FB2VMjUs0keQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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