SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b854ae6aa79c9eb25ae6d0440f59f6b8742c980381bc90483292b254d72dff5b' 
  AND token = 'PxhHXbzDsV5omLTkWYl5/PLw5pdCcupfaLVmicHQqd8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}