SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12f0db25a281f3a157f08da173e756035e24d60172457a349c3b01163e4d809a' 
  AND token = 'zzCGELG/fxB4jFVbPUQBgdonv8Nw8nSroW+Zl8t6DJA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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