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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5bb2c53b7b13093b2d0090ef69280b3828c350c2b5cef33c78261d5b21dff2e2' 
  AND token = 'OMXqVxS9ibQwL3Dykd1G3RbFhpLykcCXnSG7BpOmC/w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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