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SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '121ec2cfe34680cb3b1cf302793770a4bf32ddb5e63ddffa643bc2645cf4f929' 
  AND token = 'YEmbhFzclAnNJSEVS6Oa1rlB/Wu5/xwGwuI0AMEuhb0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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