SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4fae2fcb739398d34c62444332d1dd674ef256328682ef607260f2f94e0a568a' 
  AND token = 'I8edkffl8XIsJFTOvJRL+ljfzpMe83GJesUxoxLNDL0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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