SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '794d22075d1d0366b1ade383e83ab3a0b5100859de277bc57936443a6f57ddef' 
  AND token = 'UQDuuACtg60X+Et7V3qyiZHIUz9PdPABUNanehqRZ/A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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