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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4d5e81adb4cb16838fdaeccc2a6b4c0952522708cc01180a26ce70839a5a0b7' 
  AND token = 'ybpGzcAUmPwEkV9mf/4PE+gr+n2ZGk4fLZ+iUq4xzq0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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