SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e12cb37dddd1cc4c782c478398ab5fec58324acfe884cff20dbbc22725048fd' 
  AND token = '6/cftfeyNDjKUU2O+LDTrkfyuSkCIUAQZdzHhLu7veo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

JSON explain

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